1. Field of the Invention
The present invention relates to a suction accumulator for use in an air conditioning system, and more particularly to a suction accumulator for use in an air conditioning refrigeration system of a motor vehicle.
2. Description of the Prior Art
The use of accumulators in air conditioning systems, particularly motor vehicle air conditioning systems, is well known. In a typical air conditioning system, the compressor receives a gaseous refrigerant fluid from the evaporator and compresses the gaseous refrigerant fluid, sending it under high pressure to the condenser as a superheated vapor. Since the high pressure vapor delivered to a condenser is much hotter than the surrounding air, the heat of the high pressure vapor is given off to the outside air flowing through the condenser fins thereby cooling the refrigerant fluid. As the gaseous refrigerant fluid loses heat to the surrounding air, it condenses into a liquid refrigerant fluid. The condensed liquid refrigerant fluid then enters an orifice tube at which the pressurized liquid refrigerant fluid transforms into a gaseous state thereby absorbing heat from warm air passing through the fins of the evaporator.
After the warmed liquid refrigerant fluid changes its phase to gas it is passed from the evaporator to an accumulator. From the accumulator, the refrigerant fluid is passed back to the compressor to start the cycle over again. However, it is very important to ensure that the refrigerant gas/fluid mixture being passed back to the compressor is in a completely gaseous state. If liquid refrigerant fluid reaches the compressor it will clog it up, thus, the accumulator's main purpose is to assure that only gaseous refrigerant fluid passes to the compressor. Additionally, the accumulator injects a prescribed amount of lubricating oil into the gaseous refrigerant fluid for lubricating the compressor. Furthermore, the accumulator can be used to make sure the oil-laden gaseous refrigerant fluid is free of particulates that might also harm the compressor.
Accordingly, the accumulator of an air-conditioning system can be used to accomplish five functions, it (a) completely vaporizes the refrigerant fluid, (b) removes all water vapor, (c) traps all particulates, (d) injects a lubricant into the outgoing refrigerant fluid vapor stream, and (e) acts as a reservoir for the refrigerant fluid when system demand is low. Typical examples of accumulators accomplishing these functions are shown in U.S. Pat. Nos. 3,798,921; 4,111,005; 4,291,548; 4,496,378; 5,052,193; and 5,282,370.
Typically, a suction accumulator consists of a liquid storage vessel in which is received a generally U-shaped tube, one end of which is connected to the outlet of the storage vessel and the other end of which is opened to the interior of the vessel. As the incoming liquid refrigerant fluid flows into the vessel, it collects in the bottom of the interior and the gaseous components of the refrigerant fluid are forced, due to pressure in the accumulator and the vacuum created by the compressor, through the open end of the U-shaped tube and out of the accumulator. Oil for lubricating the compressor collects in the bottom of the vessel along with any liquid refrigerant fluid. Typically, an orifice located in the bight portion of the U-shaped tube entrains a metered amount of oil and refrigerant fluid into the fluid exiting the accumulator.
A problem with prior art accumulators is that it is necessary to introduce some type of device, such as a baffle member, to prevent liquid refrigerant fluid from exiting the accumulator or gaining access to the open end of the U-shaped tube. Thus, it is customary to employ a baffle member somewhere proximate the open inlet end of the U-shaped tube in order to prevent the liquid from entering the exit tube of the accumulator. Typically, these baffle members have a frustoconical design which serves to deflect the liquid refrigerant fluid back down into the bottom portion of the accumulator while allowing the gaseous refrigerant fluid to pass by. Examples of such devices include U.S. Pat. No. 5,052,193, to Pettitt et al., U.S. Pat. No. 4,653,282, to Gueneau; and U.S. Pat. No. 4,111,005, to Livesay. Different designs have been proposed in an attempt to achieve the above-stated objectives while trying to increase the efficiency of the accumulator and decrease the costs associated with manufacturing. Examples include U.S. Pat. No. 5,184,480 to Kolpacke, in which the typical U-shaped exit tube is replaced with a molded integral outlet tube positioned to remove the gaseous refrigerant fluid directly through the bottom of the accumulator. However, even in the accumulator of the Kolpacke patent, while there is a baffle it is still necessary to provide a tube for carrying off the gaseous refrigerant fluid from the accumulator.
U.S. Pat. No. 4,236,381, to Imral et al, and U.S. Pat. No. 4,653,282, to Gueneau, each disclose an accumulator for use in a refrigeration circuit. Each disclose that the accumulator is made up of a plurality of vessels, one contained within the other. However, Imral et al. and Gueneau also disclose that an exit tube is inserted within the accumulator for carrying off the gaseous refrigerant fluid from the accumulator. Additionally, both Gueneau and Imral et al. are directed to an accumulator which is capable of achieving a result in addition to and separate from that of being an accumulator. In particular, Gueneau discloses that the hot exhaust gases are circulated through the outer vessel to superheat the refrigerant fluid in the accumulator causing it to more quickly turn from a liquid to a gaseous refrigerant fluid. This involves costly additional structure. Imral et al. disclose that the suction accumulator is combined with the receiver of the refrigerant circuit to carry out both functions in the same device.
Accordingly, the prior art accumulators uniformly disclose and teach the use of a baffle member to prevent liquid refrigerant fluid from reaching an exit tube partially located within the accumulator and used to convey the gaseous refrigerant fluid to the compressor. The components, such as the exit tube and the baffle member, necessary to achieve the stated functions of an accumulator, add significantly to the cost, complexity and potential problems associated with prior art accumulators.
Thus, there is still a need for an accumulator for use in an air conditioning system and particularly for use in an air conditioning system of an automotive vehicle, which is more capable and more reliable in preventing liquid refrigerant fluid from reaching the inlet line of the compressor and further wherein the accumulator does not require the use of a baffle member or an exit tube such as is known in the prior art. The elimination of the baffle member and tubes of the prior art would result in significant cost savings in the manufacture of the accumulator.